The present invention relates to serial access memory devices to be used for recording serial information during a very short time period. The read-out of this stored information can usually extend over a longer period.
A shift register is generally used to record such serial information. However, when the required shift frequency needs to be high, the bit capacity of the available shift registers is rather limited. For example the circuit MC 10141 made by Motorola, Inc. has a capacity of 4 bits.
To obtain serial access memories for high bit capacity, random access memories (RAM) using a binary counter as sequential address counter have also been used. However, in this case the recording speed is limited due to precautions to be taken in order to assure that desired data information is written into the correct memory location and that no other locations are unintentionally disturbed during the write-operation (see f.i. the article of J. J. McDowell "Memory systems terminology" published in "Semi-conductor Memories, Data, Application, Reliability Report," Monolithic Memories, Inc. 1975, pages 240 to 242 and "Fairchild bipolar memory data book", 1976, pages 4-8 and 4-9).
One important reason for the limitation of the recording speed of a serial access memory consisting of a binary addressed random access memory is the dispersion of the arrival times of the address signal and the dispersion of the transitions of the write-enable signal, as will be shown hereunder.
It can be noted that it is possible to increase the recording speed by multiplexing techniques in a similar way as proposed by Brady H. Warner, Jr., in the review "Electronic design" 1, Jan. 4, 1977, page 123. However, increasing the recording speed by such multiplexing techniques is less attractive because of the complexity and high price of the corresponding device.